You know a TV show's doomed when a minor character, who's exponentially weaker and more annoying than the existing cast, suddenly gets more screen time. This is a strange breed of rat, who boards a sinking ship instead of fleeing.

The other day, I was watching Star Trek: The Next Generation reruns — and it turned out to be an episode all about Reg Barclay, the hypochondriac creep who likes to use Beverly Crusher as his holographic blow-up doll. He stars in like twenty episodes of the final season. And then I picked up the latest Buffy comic, and it was all about Andrew, the wet wiccan who inexplicably became one of the show's main characters in its last season. So, seriously: Why do annoying dweebs take over dying shows?

Usually, the arrival of the Andrew/Barclay character is a sign that the writers have run out of stories to tell about the existing cast. Hence the Reg Barclay effect, science fiction's version of the "Cousin Oliver" effect. (Actually, I realized that Reg first starred in an episode back in season three. But he definitely became more prominent in the last two seasons.) And often, this character has a few other notable qualities:

1) He/she is clearly a stand-in for the writers, being nerdy and full of exaggerated insecurity and self-mockery.
2) He/she contains qualities that existing characters already had, but they're pushed up to 11. Like, say, Andrew is like Xander on reverse-steroids, making him even weaker.
3) He/she is often put on some kind of accelerated character arc from clueless to loveable, or from good to evil, because all the other characters have already taken that journey and we need to see someone new take it.

Update: Thanks to all who commented. I had noticed that Barclay's first episode of TNG was in season three, but had been certain that he'd cropped up a lot more in seasons six and seven. But it turns out the Barclay pain was pretty evenly spread throughout seasons three, four, five, six and seven, with a slight spike in season six. He's referenced, but does not appear, in the Worf cowboy episode. So it's more accurate to say he took over Voyager, where he appears in a lot of the later episodes.

Here's our Hall Of Pain, showcasing the Reggiest Reg Barclays of SF television. Feel free to suggest your own additions, or argue with these choices:

The really annoying thing about both Andrew and Reg Barclay, of course, is that they went on to represent their respective shows on the inevitable spin-offs. While the actual cast members of TNG and Buffy were too busy trying to escape from being typecast, we got to revisit both Andrew and Reg on many, many occasions. Whenever Angel needed someone to pop up and be a mouthpiece of Buffy's new Slayer Army, Andrew fit the bill. And the final seasons of Star Trek: Voyager were almost as covered with Barclay's sweaty handprints as the final season of TNG was.

This is a plea to showrunners and TV producers everywhere — please don't Scrappy-Doo your final season. It's not worth it! If you think you're about to be canceled, don't project your anguish and insecurity onto the screen by giving us a character who has ever reason to be insecure. Don't pass your pain onto us, the viewers. And if you've run out of ideas for storylines about your actual main cast, turn them all into cyber-ninja-marmosets. We won't mind. Just please — don't inflict the Reg Barclay syndrome on us.

Note: As with everything in life, this post was greatly enriched by surfing TVTropes.org.